It is common in the construction trades to use anchor bolts to mount structural pieces and fixtures to concrete, masonry and other materials. Anchor bolts are made in a variety of types but are commonly installed by first drilling a cylindrical hole in the concrete or other material in which the anchor bolt is being installed. The holes drilled for receiving the anchor bolts are usually drilled to a specific size determined by the size of the anchor bolt being installed therein. The anchor bolts are then driven into the holes. The driving of the anchor bolts into the hole or the subsequent tightening of the nut upon the anchor bolt causes the anchor bolt to swage outwardly or otherwise form a tight connection between the anchor bolt and the surrounding concrete or other material.
For relatively small sized anchor bolts having diameters less than 3/4", it is relatively easy for the anchor bolts to be driven inwardly using a one or two pound hammer. For larger size anchor bolts, it becomes necessary to use heavy sledge hammers and considerable amounts of driving force to install the anchor bolts. Installation of anchor bolts using sledge hammers creates several problems. The first problem is that the sledge hammers typically damage the threads present on the exterior end of the anchor bolt. This problem has been obviated by using either a single nut or double nut threaded onto the end of the bolt so that the sledge hammer strikes the nut and does not mar the threads. This installation technique causes all of the driving force to be transmitted through the nut, threads of the nut, and then the threads of the bolt. In difficult installations, this impact loading of the threads can cause mechanical distortion and possibly mechanical failure of the threads themselves.
Installation of large anchor bolts using sledge hammers also is physically demanding, requiring that a person swing a relatively heavy, such as 12 pound, sledge hammer in a variety of positions. Installation of the anchor bolts in overhead locations is particularly difficult, especially where installation is high above ground and in cramped quarters.
Another problem associated with the sledge hammer technique for installing anchor bolts is that it is very difficult for the anchor bolt to be driven to a precise depth within the receiving hole. Precise depth location is desirable since the anchor bolts are preferably installed as deeply as possible within the receiving hole while still providing a sufficient number of anchor bolt threads to allow a structural plate or other fixture together with any washers and the anchor bolt nut to be positioned over the anchor bolt shank and then be tightened. It is desirable to leave approximately two exposed threads at the end of the installed anchor bolt to obtain maximum bolt performance without leaving unnecessary amounts of bolt extending beyond the nut, thereby creating potential for bending the bolt or marring the threads.
Drilling a receiving hole for an anchor bolt in concrete and masonry usually involves using a power impact hammer/drill tool which is well known in the construction trades. It is desirable that this impact hammer/drill tool also be used to perform the driving of the anchor bolt into the receiving hole. Heretofore, there has been no tool or adaptor which allowed a power impact hammer/drill tool to be used in this fashion.
It is an object of this invention to provide an anchor bolt installation tool which will allow anchor bolts to be driven into preformed receiving holes to a predetermined depth using a power impact hammer/drill tool.
These and other objects and advantages of the invention will be apparent from the detailed description given herein.